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Linking record types Schema DDL
80 U929-J-Z125-9-76
Example 1
Figure 18: Example of OPTIONAL AUTOMATIC
The link between a CUSTOMER-ORDER record and a CUSTOMER record is relatively
stable. An order only exists if a customer has placed one. The link to the owner record is
thus automatic at the time the CUSTOMER-ORDER record is stored. Filled orders are to
remain in the database for statistical purposes even when the link to the CUSTOMER
record no longer exists. This is why the set membership is defined as OPTIONAL.
CUSTOMER-
CUSTOMER-ORDERS-PLACED
(OPTIONAL AUTOMATIC)
CUSTOMER
ORDER